Magha Puja also known as Sangha Day or Fourfold Assembly Day
Magha Puja is the second most important Buddhist festival. It occurs in the month of Magh in the lunar calendar, usually between mid-January and mid-February. This festival commemorates the spontaneous assembly of 1250 disciples of Buddha coming to see him and pay their respects. At this gathering, Buddha delivered a sermon where he asked them to do good, abstain from evil, and purify the mind.
Information on Magha Puja and here.
